Allelic variations in alcohol metabolism genes (ADH1B, ADH1C, CYP2E1) and alcohol use disorder (AUD) in northeastern Brazil

Abstract

Alcohol use disorder (AUD) is a multifactorial disease caused by environmental and genetic factors. Genetic polymorphisms of the enzymes involved in alcohol metabolism influence the susceptibility to alcohol dependence. The distribution of the genetic variants varies depending on ethnicity. The aim of this study was to evaluate the effects of the polymorphisms of the three genes responsible for the degradation of ethanol, ADH1B, ADH1C, and CYP2E1 to examine the influence of these mutations on the risk for alcohol use disorder in a population from northeastern Brazil. In addition, the allelic distribution of the northeastern population will be compared with that obtained for other populations. The allelic and genotypic frequencies were determined in 163 alcoholic patients and 182 control subjects. Genotyping was performed by PCR-RFLP. The allele frequencies in the northeastern population were similar to those reported in studies in Mexico but differed significantly from those reported in studies of a Chinese population. The polymorphic variants of CYP2E1 were associated with a higher risk for alcohol use disorder [odds ratio (OR) = 2.80; 95% confidence interval (CI) = 1.35-5.83, p = 0.0072]. No significant result was obtained from the analyses of the ADH1C gene. A significant protective effect against alcohol dependence was observed in individuals carrying allelic and genotypic variations of the ADH1B gene, as determined through the combined analysis of homozygous and heterozygous variant forms of the gene in controls and alcoholics (P = 0.03). Furthermore, the combination of ADH1B*2 with ADH1C*1 and CYP2E1 (c1/c1) may confer protection against alcohol use disorder.